We prove that non-recursive base conversion can always be implemented by using a deterministic Markov process. Our paper discusses the pros and cons of recursive and non-recursive methods, in general. And we include a...We prove that non-recursive base conversion can always be implemented by using a deterministic Markov process. Our paper discusses the pros and cons of recursive and non-recursive methods, in general. And we include a comparison between non-recursion and a deterministic Markov process, proving that the Markov process is twice as efficient.展开更多
Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herei...Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herein, we report an efficient Zr-NiO catalyst with atomically dispersed Zr-dopants incorporated in NiO lattice, delivering the exceptional NO_(2)RR performance with industriallevel current density(>0.2 A cm^(-2)). In situ spectroscopic measurements and theoretical simulations reveal the construction of ZrNi frustrated Lewis acid-base pairs(FLPs) on Zr-Ni O, which can substantially increase the number of absorbed nitrite(NO_(2)~-),promote the activation and protonation of NO_(2)~- and concurrently hamper the H coverage, boosting the activity and selectivity of Zr-NiO towards the NO_(2)RR. Remarkably, Zr-NiO exhibits the exceptional performance in a flow cell with high Faradaic efficiency for NH_(3) of 94.0% and NH_(3)yield rate of 1,394.1 μmol h^(-1)cm^(-2) at an industrial-level current density of 228.2 m A cm^(-2),placing it among the best NO_(2)RR electrocatalysts for NH_(3) production.展开更多
Tin-based perovskite solar cells(TPSCs)as the most promising candidate for lead-free PSCs have incurred extensive researches all over the world.However,the crystallization process of tin-based perovskite is too fast d...Tin-based perovskite solar cells(TPSCs)as the most promising candidate for lead-free PSCs have incurred extensive researches all over the world.However,the crystallization process of tin-based perovskite is too fast during the solution-deposited process,resulting in abundant pinholes and poor homogeneity that cause serious charge recombination in perovskite layer.Here,we employed theπ-conjugated Lewis base molecules with high electron density to systematically control the crystallization rate of FASnI3 perovskite by forming stable intermediate phase with the Sn-I frameworks,leading to a compact and uniform perovskite film with large increase in the carrier lifetime.Meanwhile,the introduction of theπ-conjugated systems also retards the permeation of moisture into perovskite crystal,which significantly suppresses the film degradation in air.These benefits contributed to a stabilizing power conversion efficiency(PCE)of 10.1%for the TPSCs and maintained over 90%of its initial PCE after 1000-h light soaking in air.Also,a steady-state efficiency of 9.2%was certified at the accredited test center.展开更多
为了减小低快拍数和低信噪比下采样协方差矩阵误差,并降低其运算复杂度,提出了一种基于实数化的均匀圆阵采样协方差矩阵重构方法。针对均匀圆阵的特点,通过组建特殊的基向量,构成特殊的重构矩阵。通过将采样协方差矩阵实数化,进一步降...为了减小低快拍数和低信噪比下采样协方差矩阵误差,并降低其运算复杂度,提出了一种基于实数化的均匀圆阵采样协方差矩阵重构方法。针对均匀圆阵的特点,通过组建特殊的基向量,构成特殊的重构矩阵。通过将采样协方差矩阵实数化,进一步降低了重构矩阵的复杂度。考虑到多通道不一致性对重构矩阵的影响,引入0位校正算法,提高了重构方法的稳健性。最后应用重构后的协方差矩阵进行子空间类波达方向估计(direction of arrival,DOA)。实验仿真证明,该特殊重构矩阵在实数化下与原矩阵重构能力相同;当快拍数为100、信噪比为0 dB时,双信源分辨力较重构前由74%提高到95%以上;理论重构运算复杂度降低到原来的53.99%。展开更多
Direct synthesis of glycerol carbonate(GC)from CO_(2)and glycerol(a byproduct of biodiesel production)is a route to obtain a high-value chemical from waste and low-cost byproducts but has not yet industrialized due to...Direct synthesis of glycerol carbonate(GC)from CO_(2)and glycerol(a byproduct of biodiesel production)is a route to obtain a high-value chemical from waste and low-cost byproducts but has not yet industrialized due to the lack of efficient catalysts.Ceria(CeO_(2))exhibits the highest catalytic activity and GC selectivity among the heterogeneous catalysts studied so far.However,the mechanism of this reaction over CeO_(2)catalysts has not been studied in detail.Herein,we synthesized CeO_(2)nanocrystals with different morphologies as model catalysts that can predominantly expose(111),(110),and(100)facets,and their surface acid-base properties were characterized using high-sensitivity temperature-programmed desorption of NH3 and CO_(2)with quadrupole mass spectrometry as detector(NH3-TPD-QMS and CO_(2)-TPD-QMS).We found that the catalytic performance(GC formation rate)is strictly linearly dependent on the density of basic sites,which is relevant to the adsorption and activation of CO_(2).In addition,to illustrate a more microscopic reaction mechanisms underlying the formation of GC from CO_(2)and glycerol on all three low-index surfaces(111),(110)and(100),we also performed comprehensive first principles calculations.A three-step Langmuir-Hinshelwood(LH)mechanism was identified in which the annulation reaction is the rate-limiting step.The CeO_(2)(11)surface exhibits the lowest overall activation energy,which agrees well with the catalytic performance that the CeO_(2)nano-octahedra,predominantly exposing(111)facets,have the highest GC formation rate.This work is the first to combine experiments on shaped CeO_(2)model catalysts with first-principles calculations to gain insight into the mechanism of direct synthesis of GC from CO_(2)and glycerol,and will aid in the development of catalysts with improved performance.展开更多
文摘We prove that non-recursive base conversion can always be implemented by using a deterministic Markov process. Our paper discusses the pros and cons of recursive and non-recursive methods, in general. And we include a comparison between non-recursion and a deterministic Markov process, proving that the Markov process is twice as efficient.
基金supported by the National Natural Science Foundation of China (52161025)the Natural Science Foundation of Gansu Province (20JR10RA241)。
文摘Electrochemical NO_(2)~--to-NH_(3) conversion(NO_(2)RR) offers a green route to NH_(3) electrosynthesis, while developing efficient NO_(2)RR catalysis systems at high current densities remains a grand challenge. Herein, we report an efficient Zr-NiO catalyst with atomically dispersed Zr-dopants incorporated in NiO lattice, delivering the exceptional NO_(2)RR performance with industriallevel current density(>0.2 A cm^(-2)). In situ spectroscopic measurements and theoretical simulations reveal the construction of ZrNi frustrated Lewis acid-base pairs(FLPs) on Zr-Ni O, which can substantially increase the number of absorbed nitrite(NO_(2)~-),promote the activation and protonation of NO_(2)~- and concurrently hamper the H coverage, boosting the activity and selectivity of Zr-NiO towards the NO_(2)RR. Remarkably, Zr-NiO exhibits the exceptional performance in a flow cell with high Faradaic efficiency for NH_(3) of 94.0% and NH_(3)yield rate of 1,394.1 μmol h^(-1)cm^(-2) at an industrial-level current density of 228.2 m A cm^(-2),placing it among the best NO_(2)RR electrocatalysts for NH_(3) production.
基金supported by the National Natural Science Foundation of China(11574199,11674219,11834011)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning+1 种基金National Institute for Materials Science was supported by the New Energy and Industrial Technology Development Organization(NEDO,Japan)the KAKEHI Grant of Japan(18H02078)
文摘Tin-based perovskite solar cells(TPSCs)as the most promising candidate for lead-free PSCs have incurred extensive researches all over the world.However,the crystallization process of tin-based perovskite is too fast during the solution-deposited process,resulting in abundant pinholes and poor homogeneity that cause serious charge recombination in perovskite layer.Here,we employed theπ-conjugated Lewis base molecules with high electron density to systematically control the crystallization rate of FASnI3 perovskite by forming stable intermediate phase with the Sn-I frameworks,leading to a compact and uniform perovskite film with large increase in the carrier lifetime.Meanwhile,the introduction of theπ-conjugated systems also retards the permeation of moisture into perovskite crystal,which significantly suppresses the film degradation in air.These benefits contributed to a stabilizing power conversion efficiency(PCE)of 10.1%for the TPSCs and maintained over 90%of its initial PCE after 1000-h light soaking in air.Also,a steady-state efficiency of 9.2%was certified at the accredited test center.
基金supported by the National Natural Science Foundation of China(21133011,21373246)Hundred-Talent Programme of the Chinese Academy of SciencesLanzhou Institute of Chemical Physics,Chinese Academy of Sciences~~
文摘为了减小低快拍数和低信噪比下采样协方差矩阵误差,并降低其运算复杂度,提出了一种基于实数化的均匀圆阵采样协方差矩阵重构方法。针对均匀圆阵的特点,通过组建特殊的基向量,构成特殊的重构矩阵。通过将采样协方差矩阵实数化,进一步降低了重构矩阵的复杂度。考虑到多通道不一致性对重构矩阵的影响,引入0位校正算法,提高了重构方法的稳健性。最后应用重构后的协方差矩阵进行子空间类波达方向估计(direction of arrival,DOA)。实验仿真证明,该特殊重构矩阵在实数化下与原矩阵重构能力相同;当快拍数为100、信噪比为0 dB时,双信源分辨力较重构前由74%提高到95%以上;理论重构运算复杂度降低到原来的53.99%。
基金supported by the National Natural Science Foundation of China(No.21902005)Beihang Universityand State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology).
文摘Direct synthesis of glycerol carbonate(GC)from CO_(2)and glycerol(a byproduct of biodiesel production)is a route to obtain a high-value chemical from waste and low-cost byproducts but has not yet industrialized due to the lack of efficient catalysts.Ceria(CeO_(2))exhibits the highest catalytic activity and GC selectivity among the heterogeneous catalysts studied so far.However,the mechanism of this reaction over CeO_(2)catalysts has not been studied in detail.Herein,we synthesized CeO_(2)nanocrystals with different morphologies as model catalysts that can predominantly expose(111),(110),and(100)facets,and their surface acid-base properties were characterized using high-sensitivity temperature-programmed desorption of NH3 and CO_(2)with quadrupole mass spectrometry as detector(NH3-TPD-QMS and CO_(2)-TPD-QMS).We found that the catalytic performance(GC formation rate)is strictly linearly dependent on the density of basic sites,which is relevant to the adsorption and activation of CO_(2).In addition,to illustrate a more microscopic reaction mechanisms underlying the formation of GC from CO_(2)and glycerol on all three low-index surfaces(111),(110)and(100),we also performed comprehensive first principles calculations.A three-step Langmuir-Hinshelwood(LH)mechanism was identified in which the annulation reaction is the rate-limiting step.The CeO_(2)(11)surface exhibits the lowest overall activation energy,which agrees well with the catalytic performance that the CeO_(2)nano-octahedra,predominantly exposing(111)facets,have the highest GC formation rate.This work is the first to combine experiments on shaped CeO_(2)model catalysts with first-principles calculations to gain insight into the mechanism of direct synthesis of GC from CO_(2)and glycerol,and will aid in the development of catalysts with improved performance.
